Location services have been used as a means to comply with FCC requirements for emergency 911 services (better known as E911), and for commercial purposes such as navigation, and marketing in a push-pull advertising environment. Several automation techniques have been used for locating a mobile device such as, for example, TDOA (Time Difference Of Arrival), Enhanced Observed Time Difference (E-OTD), Angle of Arrival, Cell of Origin, and assisted GPS.
The issue with these techniques is that in-building interference or other obstructions substantially reduce the accuracy of locating the mobile device. Accuracy becomes especially important under emergency conditions. TDOA systems typically provide a location estimate that barely meets the FCC E911 mandate of 50 meters with a 67% confidence level, and 150 meters with a 95% confidence level. GPS (Global Positioning Systems) also fail to meet these requirements when the mobile device is inside a building, thereby interfering with the mobile device's line-of-site access to GPS satellite constellations roaming Earth's orbit.
A need therefore arises for a method and apparatus for improving location services.